In the construction of homes, apartments, offices, and other buildings, the use of lap joints is common to provide an asethetically pleasing joint between abutting end regions of adjacent wooden or plastic workpieces. For example, in finishing the interior of a building, lap joints are provided between abutting wall moldings, chair railing, wainscoting railing, and the like to impart a pleasing appearance to the joint. In finishing the exterior of a building, lap joints are provided between abutting siding boards, fascia boards, deck boards, and the like to this same end.
In the past, a carpenter installing wall molding, chair railing, or wainscoting railing, typically would measure the wall for dimension and attempt to cut two separate molding or railing pieces to proper dimension with an angled cut at the ends thereof to be overlapped to form a lap joint when the molding or railing pieces are fastened to the wall. However, for even a skilled carpenter, the measuring and cutting of the separate molding or railing pieces sometimes occurs in a trial and error manner in order to achieve the desired aesthetically pleasing lap joint after the pieces are fastened on the wall. For example, should the measured dimension and/or angled cutting be in error even to a small extent, then the resulting lap joint between the molding or railing pieces after fastening on the wall is less than visually appealing and may require recutting additional molding or railing pieces and/or in touching-up of the lap joint with filler, both of which are time consuming and add to the cost of installing the molding or railing on the wall.
Moreover, in construction of shelving and other structures, the sides of one or more workpieces can be routed out using a power router to form a groove or routed region in a side of workpeice in order to receive an interconnecting member such as a shelf board.